Gareth Ainsworth picked Blackstock out after getting the better of Michael Gray on the right flank, only for the striker to poke the ball wide of the near post.
That was the best chance of an uninspiring first half in which Wolves' Wayne Hennessey was the busier goalkeeper.
Hennessey twice dived to tip away long-range efforts from Martin Rowlands, and comfortably held Akos Buzsaky's free-kick and Ainsworth's tamely-struck shot.
Wolves rarely threatened but did go close to scoring shortly before the break when Darron Gibson sent a left-foot shot wide of the target.
The visitors survived a scare two minutes after the interval, when defender Neill Collins allowed the ball to bounce over him near the edge of the penalty area and Blackstock volleyed wide.
Rangers kept the pressure up and had appeals for a penalty waved away after striker Marc Nygaard appeared to be bundled over in the area by Kevin Foley.
Wolves looked unimpressive throughout but should have gone ahead in the 70th minute. Gibson's right-wing cross presented Elliott with a simple chance but he nudged the ball wide when it seemed easier to score.
A defeat would have been tough on Rangers, who battled hard and were unlucky not to score a late winner.
Hennessey did well to push Rowlands' drive over the bar and Ainsworth fired inches wide in the closing stages.